    public class Trapezoid extends Shape
    {


        private double top ;
        private double bottom ;
        private double height ;
        public Trapezoid( double top , double bottom , double height )
        {
            super("梯形");
            this.top=top;
            this.height=height;
            this.bottom=bottom;
            // 直接在 Trapezoid 类中书写该构造⽅法是⽆法编译的，你需要解决这个编译错误
        }
        public void calculate()
        {
            area=(top+bottom)*height*0.5;
        }
    }
